[Milsurplus] PE-237 Output Voltage

[WA5CAB at cs.com]

Group,

I am repairing a PE-237 that is to go into a Weasel.  Aside from one 
problem with the 6 volt relay supply (which I hope to find and fix tonight or 
tomorrow) everything seems to work.  But the no-load output of the high B+ is 
around 800 volts.  It drops a little bit if the radio is connected but not 
keyed but is still above 700 volts.  The receiver continues to run OK off of 
the regulated 105 volt line.  But I hadn't expected the B+ to be this high.  
Several years ago I repaired and sold another one and the radio 
(coincidentally it also went into a Weasel) but don't recall the B+ being this high.  I 
don't know yet what it drops to with the transmitter working because of the 
afore mentioned relay supply problem.

If anyone has a working set and can do so, I would appreciate it if you 
would measure the 500 volt line's actual voltage with the radio disconnected 
and tell me what it is.  And also the voltage with everything hooked up and 
with the mode switch on the transmitter in SEND but the transmitter not keyed. 
 There is an interlock to disable the power supply if the receiver is not 
present.  To override the interlock you will need to connect a resistor 
across the receiver filament line.  On the terminal strip above the output 
connector in the PE-237 this is from terminal 22 to terminal 24 (24 is ground and 
common for everything).  Running off of a 12 volt supply, I determined 
experimentally that at least in this supply, 10 ohms is low enough (I paralleled 
two 20 ohm 2 watt carbon comp resistors I happened to have).  Then, with the 
supply turned on, you have to ground terminal 36 to put the supply into 
high power mode (starts the VB-16).  The 500 volt line is on terminal 32.  The 
terminal strip numbers are the same as the output connector socket contact 
numbers (the terminal strip itself is not shown on most schematics).  Be sure 
to set your multimeter to 1000 VDC or higher before grounding terminal 36.  
And remove the resistor and the wire you used to switch the supply into 
high power before reconnecting the CD-1086 to the radio.  And don't loosen the 
screws in the terminal strip any more than necessary when you are attaching 
the resistor.  If it gets loose and falls below the top of the chassis 
you've got a real problem!!!

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480